Optical Fiber Connector with Changeable Polarity

ABSTRACT

A multi-fiber, fiber optic connector may include a reversible keying arrangement for determining the orientation for plugging the connector into an adapter to thereby allow for a change in polarity of the connection to be made on site. The connector housing may be configured to engage with a removable key that may be engaged with the housing in at least two different locations to provide the plug-in orientation, or the housing may have slidably displaceable keys movable between multiple positions on the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 14/637,314, filed Mar. 3, 2015, the contents of which is incorporated by reference in its entirety as if fully set forth herein.

BACKGROUND

Demand for bandwidth by enterprises and individual consumers continues to experience exponential growth. To meet this demand efficiently and economically, data centers have to achieve ultra-high density cabling with low loss budgets. Fiber optics have become the standard cabling medium used by data centers to meet the growing needs for data volume and transmission speeds.

Individual optical fibers are extremely small. For example, even with protective coatings, optical fibers may be only about 250 microns in diameter (only about 4 times the diameter of a human hair). As such, hundreds of fibers can be installed in cables that will take up relatively little space. For connections between cables, however, the fibers are terminated with connectors. Multiple fibers may be arranged within a single connector. For example, multi-fiber connectors such as those using multi-fiber push-on/pull-off (MPO) technology may contain and connect 12 or 24 fibers. Connectors, such as MPO type connectors, generally include a housing portion that contains a ferrule that terminates the ends of the fibers. Ferrules are generally used to retain the ends of the optical fibers for connecting the optical fibers. One type of optical ferrule that may be used with MPO type connectors is an MT (Mechanically Transferable) ferrule.

Typically, MPO connectors are joined together to connect the optical transmission path of one fiber optic cable to another fiber optic cable or device, and the connection may be made by inserting the MPO connectors in an MPO adapter. An adapter generally includes a housing, or portion of a housing, having at least one port which is configured to receive and hold a connector to facilitate the optical connection of the connector ferrule with the ferrule of another connector or other device. Adapters may be used to facilitate connections contained within a chassis. The term “chassis” as used herein broadly refers to a containment structure for housing electrical components or switching components.

As a result of the use of pre-terminated fiber assemblies, the issue of maintaining polarity in parallel fiber-optic links is becoming increasingly important. Described simply, polarity maintains proper continuity between transmitters and receivers. In order to make sure that connectors are mated correctly with an adapter, the connector and adapter typically include fixed keying features that permit the connector to be mated with the adapter in generally only one mating configuration. While this has the advantage of preventing a connection that has the wrong polarity, it also can makes it difficult to change the polarity of the connection on site.

Therefore, there remains a need for multi-fiber, fiber optic connectors that have the flexibility of easily changing the polarity of the connector on site.

SUMMARY

So that the polarity of a multi-fiber, fiber optic connector may be changed, a housing of the connector may be configured to include a removable key that may be positioned at alternate locations on the housing. To change the polarity, the key may be moved from one location to another.

A multi-fiber fiber optic connector includes a ferrule having a plurality of optical fibers supported therein, and a housing disposed around at least a portion of the ferrule. The housing has a first end for being inserted into a fiber optic adapter, a second end disposed opposite the first end, and at least a first wall portion extending from the first end towards the second end and a second wall portion opposite the first wall portion and extending from the first end towards the second end, wherein each of the first wall portion and the second wall portion have an internal surface disposed towards the ferrule and an external surface disposed outwardly away from the ferrule. The housing defines a longitudinal axis in a direction from the first end to the second end, a transverse axis orthogonal to the longitudinal axis, and a vertical centerline through the first and second wall portions. The connector also includes a key configured to be removably attached to either the first wall portion to define a first keyed configuration for insertion of the first end into the adapter in only a first orientation to define a first polarity with respect to the adapter, or the second wall portion to define a second keyed configuration for insertion of the first end into the adapter in only a second orientation to define a second polarity with respect to the adapter, wherein the second polarity is opposite to the first polarity. The key includes a first end configured for engaging with the housing adjacent the first housing end to prevent movement of the first key end with respect to the housing in at least a direction laterally away from the housing when removably attached to either the first wall portion or the second wall portion, and a second end disposed longitudinally away from the first end and configured for being removably attached to the housing at a second location of the housing spaced longitudinally from the first end of the housing towards the second end of the housing to prevent movement of the key with respect to the housing in at least a longitudinal direction along the housing when removably attached to either the first wall portion or the second wall portion.

In an embodiment, a housing for a fiber optic connector includes a first end for being inserted into a fiber optic adapter, and a second end disposed opposite the first end, and the housing defines a longitudinal direction from the first end to the second end, and a transverse direction orthogonal to the longitudinal direction. The housing also includes at least a first wall portion extending from the first end towards the second end and a second wall portion opposite the first wall portion and extending from the first end towards the second end, wherein each of the first wall portion and the second wall portion have an external surface disposed outwardly away from the ferrule. The housing also includes a key configured to be removably attached to either the first wall portion to define a first keyed configuration for insertion of the first end into the adapter in only a first orientation to define a first configuration with respect to the adapter, or the second wall portion to define a second keyed configuration for insertion of the first end into the adapter in only a second orientation to define a second configuration with respect to the adapter. The key includes one of a snap-in fastener and a twist lock fastener configured for engaging with either the first wall portion or the second wall portion, and each of the first wall portion and the second wall portion comprises an opening configured for receiving the snap-in fastener or the twist in fastener to releasably retain the key with either the first wall portion or the second wall portion.

In an embodiment, a method is provided for switching the polarity configuration between a multi-fiber fiber optic connector and a corresponding adapter configured for receiving the connector. The connector has a connector housing comprising a first end for being inserted into the adapter, a second end disposed opposite the first end, and at least first and second movably displaceable keys displaceable along the housing between a first position adjacent the first end and a second position disposed towards the second end. One of the first and second keys may be in its first position and the other of the first and second keys may be in its second position to provide a first polarity for the fiber optic connector. The method includes slidingly displacing the first key from its corresponding first or second position to the other of the first and second positions, and slidingly displacing the second key from its corresponding first or second position to the other of the first and second positions, to provide a second opposite polarity for the fiber optic connector.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts perspective views of an MPO connector and adapter according to an embodiment.

FIGS. 2A and 2B depict mating/polarity configurations of MPO connectors according to an embodiment.

FIGS. 3A and 3B are representative top and bottom perspective views of a fiber optic connector housing with a detachable key for changing the polarity of the connector according to an embodiment.

FIG. 4 is a perspective view of a partially disassembled fiber optic connector housing according to the embodiment of FIGS. 3A and 3B.

FIGS. 5A-5D are bottom, top, end and side views of a key according to the embodiment of FIGS. 3A and 3B.

FIGS. 6A-6E are face, side, cross-sectional and detail views of the fiber optic connector housing according to the embodiment of FIGS. 3A and 3B.

FIG. 7 is a perspective view of an alternative key according to an embodiment.

FIG. 8 shows the key of FIG. 7 positioned on a connector housing according to an embodiment.

FIGS. 9A-9C are face, cross-sectional and detailed views of a connector of the embodiment of FIG. 8.

FIGS. 10A and 10B are different perspective views of an alternative key according to embodiment.

FIGS. 11A-11C are various views of a connector with the key of FIGS. 10A and 10B according to an embodiment.

FIGS. 12A and 12B are different perspective views of an alternative key according to an embodiment.

FIGS. 13A-13C are various views of a connector with the key of FIGS. 12A and 12B according to an embodiment.

FIGS. 14A and 14B are perspective views of a connector with movable keys according to an embodiment.

FIGS. 15A and 15B are views of components of the connector of FIGS. 14A, 14B with the outer housing removed according to an embodiment.

FIGS. 16A-16C show top, side and cross-sectional views of the connector or FIG. 14A, 14B according to an embodiment.

FIGS. 17A-17F are various views of the moveable key of FIGS. 14A, 14B according to an embodiment.

FIGS. 18A-18D show views of the inner and outer housing components of the connector of FIGS. 14A, 14B according to an embodiment.

FIGS. 19A-19E show sequential views (top and cross-sectional) of the process of switching the polarity of the connector of FIGS. 14A, 14B according to an embodiment.

FIGS. 20A-20C show side and detailed views of the connector of FIGS. 14A, 14B according to an embodiment.

FIGS. 21A-21C are views of an alternative movable key according to an embodiment.

FIG. 22 provides a top view of an inner housing for the key of FIGS. 21A-21C according to an embodiment.

FIGS. 23A-23C show cross-sectional views of a connector assembly with the keys of FIGS. 21A-21C according to an embodiment.

FIG. 24 is a perspective view of a connector having a ‘snap-in’ key according to an embodiment.

FIG. 25 is a top view of the inner housing of the connector of FIG. 24 according to an embodiment.

FIGS. 26A-26D show bottom, side, end and detailed views of a snap-in key according to an embodiment.

FIG. 27 is a perspective view of an ‘twist-lock’ insertable key according to an embodiment.

FIGS. 28A-28C are bottom, end and side views of the key of FIG. 27 according to an embodiment.

FIG. 29 is a top view of the inner housing of a connector for the key of FIG. 27 according to an embodiment.

FIGS. 30A and 30B show representative views of an internal side of a housing wall for engaging with the key of FIG. 27 according to an embodiment.

DETAILED DESCRIPTION

As used herein, the term “optical fiber” is intended to apply to all types of single mode and multi-mode light waveguides, including one or more bare optical fibers, coated optical fibers, loose-tube optical fibers, tight-buffered optical fibers, ribbonized optical fibers, bend performance optical fibers, bend insensitive optical fibers, nanostructured optical fibers or any other expedient for transmitting light signals. A multi-fiber optic cable includes a plurality of the optical fibers. Such cables have a variety of names depending on their particular usage, and may be considered as “trunk cables” or “trunks” when connected to fiber optic modules used to form connections to jumper cables using a select polarity.

For connection of cables together or with other fiber optic devices, the terminal ends of a cable may include a connector. A connector may include a housing structure configured to interact with and connect with an adapter. An adapter, in a simple form, may include two aligned ports for aligning fiber optic connectors therein to align and connect optical fibers end-to-end. As described herein, the connectors and adapters may be considered multi-fiber connectors and multi-fiber adapters.

While the following description is directed towards MPO adapters and MPO connectors with MT optical ferrules, the embodiments described may be applicable to other adapters, connectors and ferrule types as well. An embodiment of an MPO connector 10 and adapter 12 are generally represented in FIG. 1. A first end of the connector 10 may include a ferrule 14 that may be a multi-fiber ferrule as shown. In addition, the connector 10 may have attached thereto, a fiber optic cable 15 a and cable boot 15 b (shown only schematically) that may extend from a second end of the connector.

An adapter 12 may include a first end 16 having a first plug-in port 18 for receiving the ferrule end of an optical fiber connector 10 therein, and may include a second end 16 having an additional plug-in port 22 (not visible) for receiving an additional MPO optical fiber connector, or other type of fiber optic device therein.

For retention of an MPO connector 10 within each of the ports 18, 22 the ports may be provided internally with a connector clip that may be formed by the two resilient tabs 24 a, 24 b configured to be displaceable outwardly for insertion and removal of a connector 10 into or out of the ports 18, 22, and return to essentially their original position to engage and retain a connector in the ports. Adapters 12 may be configured to be mounted on a chassis panel, and may include mounting flanges 26 a, 26 b to mount the adapter via screws, for example.

A connector 10 may include an inner housing 26 that may surround the ferrule 14. In the embodiment depicted, ferrule 14 is of the female type—a pairing connector may have a male-type ferrule with two guide pins that fit into the receiving holes of the female ferrule. A connector 10 may also include an outer housing member 28 that may be slidably disposed about the inner housing 26 adjacent the second end of the connector 10. To provide for a pre-determined alignment of the fiber optic cables within the adapter 12, the inner housing may include an alignment key 30 that is configured to fit within keying slot 32 of the adapter. For example, in the embodiment depicted, one of the connector 10 or adapter 12 will need to be rotated about its axis 180° to align the key 30 with the slot 32. Inner housing 26 may slide into port 18 until tabs 24 a, 24 b engage into slots 34 a, 34 b of the inner housing. The outer housing 28 may be moved towards the second end to allow the tabs 24 a, 24 b to engage into slots 34 a, 34 b, and to retain the tabs in the slots, the outer housing may be slid back towards the first end and over the tabs. The outer housing 28 may be biased towards the first end via springs (shown for example in FIG. 6D) or alternative types of biasing devices.

FIGS. 2A and 2B represent the two different modes of connection alignment to provide for the two different modes of polarity. FIG. 2A may be indicated as representing what may be termed a ‘normal’ polarity wherein fiber No. 1 of the connector 10 a may mate with fiber No. 1 of connector 10 b, and similarly, fiber No. 12 of the connector 10 a may mate with fiber No. 12 of the connector 10 b. For this type of alignment, the key 30 may be disposed adjacent side A of the ferrule, and the adapter may be keyed accordingly, with the slots 32 (FIG. 1) in correspondingly opposed surfaces within the adapter 12. To reverse the polarity of the connection between connectors 10 a, 10 b, as shown in FIG. 2B, the key position of the key 30 of connector 10 b would need to be changed to the opposite surface for reversed alignment in an adapter 12, fiber No. 1 of the connector 10 a may mate with fiber No. 12 of connector 10 b, and similarly, fiber No. 12 of the connector 10 a may mate with fiber No. 1 of the connector 10 b. Alternatively, the key 30 of the connector 10 a could be changed, or in a further embodiment, a different type of adapter may be used, wherein the slots 32 may be aligned on the same internal surface within the adapter 12.

Since an adapter 12 may already be permanently mounted on a surface, and may have a cable plugged into a back side thereof, an embodiment wherein the location of key 30 may be changed would provide for a quick, onsite polarity change. An embodiment of a connector 110 having a detachable key 130 is represented in FIG. 3. For clarity, the ferrule and any cable and cabling components are omitted. The connector may include an inner housing 126 and an outer housing 128. The inner housing may have a top side wall 126 a and a bottom side wall 126 b that may be disposed opposite one another, or rotationally, 180° from one another about a central longitudinal axis 140. The designation top and bottom are used for reference only as per the orientation shown, and could alternatively be interchanged. In an embodiment, each of the side walls 126 a and 126 b may be similar, or essentially the same, and each side wall may include a corresponding slot 132 a and 132 b that is configured for receiving the key 130. At least a portion of the key 130 may be configured to be removably insertable into either of the slots 132 a and 132 b. The key 130 may be configured in conjunction with the walls 126 a and 126 b to be removably attached with either the top wall 126 a or the bottom wall 126 b. In an embodiment, when key 130 is disposed with the top wall 126 a, the connector 110 may be configured to define a first keyed configuration for insertion of the first end of the connector into an adapter in only a first orientation to define a first polarity with respect to the adapter. Alternatively, when key 130 is disposed with the bottom wall 126 b, the connector 110 may be configured to define a second keyed configuration for insertion of the first end into the adapter in only a second orientation to define a second polarity with respect to the adapter. As discussed previously, the second polarity may be considered to be opposite to the first polarity.

FIG. 4 shows a partially disassembled view of the connector 110 of FIGS. 3A and 3B. In an embodiment, as shown in greater detail in FIGS. 5A-5D, the key 130 may include a body portion 150 that may include a slot or hole 151 at a first end of the key, and a guide rail 152 at a second end of the key. The guide rail 152 may be configured to fit within either of the slots 132 a, 132 b to guide longitudinal movement of the key 130 into a slot, and also prevent side-to-side (lateral) movement of the key once inserted in the slot. The guide rail 152 and slots 132 a, 132 b may also be configured with respect to one another to prevent the key from moving out of the slot in a direction transverse to the longitudinal axis. In an embodiment, the width of the slots 132 a, 132 b may widen in a direction from the external surfaces of the housing to the internal surface. The guide rail 152 may be correspondingly configured, as shown in FIG. 5C to have a narrower width adjacent the body 150 and widen in a direction extending away from the base. With such a configuration the key 130 may essentially be prevented from being lifted upwardly away from the housing 126 once inserted in a slot 132 a or 132 b, while also being prevented from moving laterally on the housing.

To engage the key 130 longitudinally with respect to the housing 126, the housing may include a projection 160 over which the key body 150 may be inserted to engage the projection within the hole 151. The projection 160 may be tapered outwardly away from the housing in at least the insertion direction to facilitate movement of the key body 150 up and over the projection. To facilitate removal of a key 130, once engaged with the projection 160, the key body may include at least one gripping ridge 154, or alternatively a plurality of ridges (as shown) disposed along the body 150. The ridges may be configured to be engaged, for example with a fingernail, to pull the key from the housing 126.

Additional details of the connector housing 110 may be seen in the views represented by FIGS. 6A-6F. FIGS. 6A and 6B show representative face and side views of the connector 110 with the key 130 installed. FIG. 6C is a cross-sectional view along line C-C in FIG. 6A, and FIG. 6D is a cross-sectional view along line D-D in FIG. 6B. As mentioned previously with regard to FIG. 1, the outer housing 128 may be slidably disposed about the inner housing 126 and a spring 170 may be provided to bias the outer housing forwardly, or towards the first, or insertion end of the inner housing as represented in FIG. 6D. Tabs 129, as shown in detail in FIG. 6E, may be configured to limit forward movement of the outer housing 128 along the inner housing 126.

The outer housing 128 may be moved rearwardly on the inner housing by a distance d1. Movement of the outer housing over the distance d1 provides access to the slots 134 for engagement into the slots of adaptor tabs (such as tabs 24 a, 24 b in FIG. 1) for engagement of the connector 110 within an adapter. Similarly, the outer housing 128 may be displaced by the distance d1 to release the adapter tabs for removal of the connector 110 from the adapter. FIG. 6E shows a detailed view of the interconnection between the key body 150 and hole 151 with the projection 160 of the inner housing 126. As shown in FIG. 6E, the second end of the body 150 may fit between the inner housing 126 and outer housing 128. As such, in an embodiment, the outer housing 128 may be displaced by the distance d1 to provide clearance for the key to be inserted onto the inner housing 126. When the outer housing 128 is biased forwardly as shown, the key body 150 may be prevented from being released from the projection 160. To remove the key 130, the outer housing 128 may be slid rearwardly by the distance d1 to provide clearance for lifting of the key body 150 outwardly away from around the projection 160 as shown in FIG. 6F.

An alternative embodiment of a removable key 230 is depicted in FIG. 7. In the embodiment of FIG. 7, the guide rail 252 may essentially be similar to the guide rail 152 as discussed above. Alternatively, the guide rail 152 may have an alternative configuration. The gripping surface may include at least one groove 254 that may function in essentially the same manner as the ridges 154 as discussed above, that is, to provide a surface that may be readily engaged to slide the key 230 from the inner housing 226. In an embodiment, the key 230 may have a solid key body 250 at the first end 231, or alternatively, as shown, may include an elongated slot 251 that may provide various functions as set forth further herebelow.

In an embodiment as represented in FIGS. 7 and 8, the configuration for releasably retaining the key 230 with the inner housing 226 may include lateral tabs 256 a, 256 b at the first, or insertion end 231 of the key body 250. The lateral tabs 256 a, 256 b may be configured to define corresponding lateral recesses 258 a, 258 b. The top or bottom surface 226, in addition to having slots for receiving the guide rail 252 (not shown, but essentially similar to slots 132 a, 132 b in FIG. 4), may include projections 272 a, 272 b configured to straddle the key body 250 wherein the width between the projections may be substantially the same as the width of the key body between the lateral recesses 258 a, 258 b.

The key 230 may be engaged with the inner housing 226 by insertion of the first key end 231 between the projections 272 a, 272 b. By including a slot 251 between the lateral tabs 256 a, 256 b at the first end 231, the tabs may more easily be deflected inwardly to allow for the tabs to pass between the projections 272 a, 272 b. Alternatively, if a slot 251 is not included, some polymeric materials of which the key may be constructed, may be resilient sufficiently to allow for inward compression of the tabs 256 a, 256 b to permit the tabs to move past the projections 272 a, 272 b. Once past the projections 272 a, 272 b, the tabs 256 a, 256 b may again push outwardly and retain the key 230 in engagement with the inner housing 226, at least in the longitudinal direction of insertion of the key.

The thickness of the body 250 at the first end 231 may essentially be the same as the space defined between the inner housing 226 and an outer housing 228 (FIGS. 9A-9C) so that the key 230 cannot be lifted away from the inner housing when the outer housing is in place, ensuring that removal of the key 230 must be done by longitudinal displacement of the key from between the projections 272 a, 272 b.

FIGS. 9A-9C show an alternative embodiment of an outer housing 228. In conjunction with the key 230 having a slot 251, the inside of the outer housing may include a guide 275 that is configured to fit within the elongated slot for movement within the slot upon movement of the outer housing longitudinally along the inner housing 226. In an embodiment, the guide 275 could also provide an additional stop for hindering longitudinal withdrawal of the key 230 from between the inner housing 226 and outer housing 228. When the outer housing 228 is in its forward biased position as shown, the thickness of the key body 250 may be essentially the same as the distance between the inner and outer housings. As such, upon an initial movement of the key 230 in a longitudinally downward in the figure, the slot 251 would move along the guide 275 until the inner surface 231 a of the first end 231 would contact the guide, thereby hindering further outward movement of the key.

So that the first end 231 of the key 230 may pass into the space between the inner housing 226 and outer housing 228, the inner housing may include a recess 276 that has a depth into the housing that is sufficient to permit the first end to pass between the guide 275 and the inner housing. In an embodiment as represented in FIGS. 9B and 9C, the deepest part of the recess 276 may be located at a position along the inner housing 226 that corresponds to a location at which the guide 275 might be located upon displacement of the outer housing 228 towards the back end of the inner housing. As such, when the outer housing 228 is biased forward into its normal use position, the key 230 will not pass between the guide 275 and the inner body 226. The key 230 may only pass when the outer housing 228 is first displaced towards the back end of the inner housing 226.

In the various embodiments disclosed herein, the keys and housing components, may be formed of rigid polymers or metals, for example. In general, any type of substantially rigid material may be used. The material should have a rigidity sufficient to retain the necessary engagement between the key and the housing so that the key remains in place except when a force is applied to remove the key.

Another embodiment of a key 330 is shown in FIGS. 10A and 10B. The key 330 may, for example, be a formed metal band or rigid polymer. The key 330 may include a longitudinal body 350 having a first end 350 a and a second end 350 b. A connector 310 in conjunction with a key 330 is represented in FIGS. 11A-11C. At the front end 327, each of the sidewalls 326 a and 326 b may include a recess or notch 280 that is configured to receive the second end of the key 330 therein. The second end 350 b may be hooked, or U-shaped to provide a bent flange 352 configured to fit around the front end 327 of the inner housing 326. Such a configuration of a hook and notch may prevent lateral movement of the key 330 on the sidewalls 326 a and 326 b, and may prevent movement transversely away from the housing, or a lifting off from the housing via the second end.

The first end 350 a of the key 330 may include a tab 353 that extends substantially orthogonally from the body 350. As represented in FIGS. 11B and 11C, the inner housing may have a recess, slot or hole 382 configured for receiving the tab 353 therein. Once tab 353 is engaged within the slot 382, longitudinal movement of the key 330 may be inhibited. As shown in FIG. 11A, outer housing 328 may prevent the first end 350 a of the key 330 from being lifted away from the inner housing 326, so that when the outer housing is biased into its forward position, the key 330 is essentially locked in place on the housing.

Outer housing 328 may be displaced rearwardly for installation and removal of the key 330. For installation, the outer housing 328 may be displaced rearwardly against the bias of springs (not shown, but discussed previously). The flange 352 may be aligned with the notch 380 and the key may be slid longitudinally into place with the flange in the notch to align the tab 353 with the slot 382. Tab 353 may be pushed into the slot 382 and the outer housing 328 may be released to move forwardly to cover the first end 350 a of the key 330 and hold the key in place. This procedure may be reversed for removal of the key 330. Outer housing 328 may be displaced rearwardly, tab 353 may be lifted out of the slot 382, and the key may be slid longitudinally off of the inner housing 326.

In an alternative embodiment, as represented in FIGS. 12A, 12B and 13A-13C, a key 430 may be configured to releasably connect with the outer housing 428. The key 430 may include a longitudinal body portion 450 and a guide rail 452 on the second end 450 b. The guide rail 452 may be configured to engage in a slot 432 a, 432 b of the inner housing 426 in a manner as described earlier with regard to FIGS. 6A-6E. In an embodiment, instead of a hole at the insertion end, the body 450 may include a projection 455 that extends away from the body. To engage with the projection 455, as shown in detail in FIG. 13C, the outer housing 428 may include a receptacle 490 into which the projection may extend when the outer housing is in place around the inner housing 426.

Similar to earlier embodiments, the second end 450 b of the key 430 may be retained in the slots 432 a, 432 b in the lateral and transverse directions by the configuration of the guide rail 452. The second end 450 b may essentially be movable in only the longitudinal direction upon insertion or removal of the key 430. When inserted, the first end 450 a of the key 430 may be held in place from lateral movement by a pair of projections 492 extending from the inner housing and defining a space therebetween that is essentially the same as the width of the body portion 450. The outer housing 428 may include depressible tabs 488 that, when pressed down, press downwardly on the first end 450 a to release the projection 455 from engagement in the receptacle 490.

In an alternative embodiment, as shown in FIGS. 14A, 14B, 15A, 15B, 16A, 16B and 16C, instead of a single key that may be alternatively placed in conjunction with each face of the top or bottom sidewalls of the connector, a connector 510 may be configured so that each sidewall 526 a, 526 b includes a corresponding displaceable key 530 a, 530 b. Similar to previous embodiments, the connector 510 may include an inner housing 526 with a longitudinally displaceable outer housing 528 disposed about the inner housing. Each sidewall 526 a, 526 b may include a longitudinal slot 532 a, 532 b that extends forwardly from the rear end of the inner housing 526, and as discussed further below, the keys are movably disposable along the lengths of the slots. Depending on the desired polarity, one of the keys 530 a or 530 b may be positioned forwardly in the slots 532 a, 532 b, while the other is positioned out of the way, or hidden under the outer housing. In an embodiment, the width of the slots 532 a, 532 b may widen in a direction from the external surfaces of the housing to the internal surface.

As shown in FIGS. 17A-17F, each key 530 may include a key body 550 and a projecting guide rail 552, similar to the key 130 as previously discussed with reference to FIGS. 5A-5D. Projecting rails 552 may have a narrower width adjacent the body 550 and either widen in a direction extending away from the body, or have a base portion disposed away from the body that has a width greater than the width adjacent the body. Slots 532 a, 532 b may include an enlarged entry port 533 a, 533 b that has a width sufficient to allow for passage of the guide rail 552 therethrough. FIG. 16B shows the key 530 a disposed over the slot 532 a with the guide rail 552 over the entry port 533 a, and the key 530 b disposed within the slot 532 b. Once inserted through the entry ports, the keys 530 a, 530 b may be displaceable longitudinally along the slots 532 a, 532 b, and once moved forwardly from the entry ports may not be lifted out of the slots in a direction transverse to the longitudinal direction of the slots due to the configuration of the guide rail with the greater width disposed away from the body.

FIGS. 18A-18D depict the inner housing 526 and outer housing 528. In an embodiment, the inner housing 526 may include stops 529 configured to limit the forward movement of the outer housing 528 under bias of the springs 570. The outer housing may have a front end 528 a for being disposed towards the front end of the inner housing 526 when disposed on the inner housing, and a rear end 528 b disposed opposite the front end. The outer housing 528 may include internal stops 561, that may be disposed adjacent the rear end 528 b, and configured for engaging with the stops 529 of the inner housing 526. A forward facing surface of the stops 529 may be sloped angularly upwards towards the rear of the inner housing so that the outer housing can be forced over the stops when the outer housing is slid onto the inner housing from the front end of the inner housing.

FIGS. 19A-19E represent the operation of the displaceable keys 530 a, 530 b in relation to the displaceable outer housing 528 and inner housing 526. FIG. 19A represents a connector configured with a first polarity with key 530 a in a forward ‘active’ position and key 530 b in a hidden ‘inactive’ position. To change the polarity, the outer housing 528 may be displaced rearwardly on the inner housing 526 as shown in FIG. 19B. After displacing the outer housing 528, key 530 will be partially exposed. Key 530 a may be slid rearwardly out of its ‘active’ position into its ‘inactive’ position and, as shown in FIG. 19C, both keys may be in their ‘inactive’ position. Key 530 b may be slid forwardly out of its ‘inactive’ hidden position into its ‘active’ position as shown in FIG. 19D, and the outer housing 528 may be released to return to its forward position as represented in FIG. 19E.

While the above-described sequence represents one mode of switching the polarities, the sequence of movements may be altered. For example, key 530 b may be moved forwardly prior to moving key 530 a rearwardly. To hold the keys 530 a, 530 b in the forward, or rearward position, the outer housing and/or keys may include a stop/retention configuration. In an embodiment as represented in FIGS. 20A-20C, (see also FIG. 18A) the exterior surfaces of walls 526 a, 526 b may include a ridge 563 a positioned corresponding to the forward position of a key, and a ridge 563 b positioned corresponding to a rearward position of a key. The keys 530 a, 530 b, as represented in FIGS. 17A-17E may include a corresponding slot 565 (FIGS. 17B, 17C, 17F) for engaging with either of the ridges 563 a or 563 b depending on the location of the key. Each key 530 a, 530 b may therefore be moveable longitudinally over the ridges and when the slots engage with a ridge, the frictional engagement between the keys and the housing will increase and a person working with the connector will be able to feel when engagement occurs. Once engaged, an additional amount of force would then be needed to move the keys from their engaged positions. Alternative configurations of engagement features may also be provided. As an example, as previously discussed with reference to FIGS. 7 and 8, lateral projections and recesses, similar to projections 256 a and recesses 258 a may be provided on the sides of a key 530 a, 530 b and the housing surface could include a projection such as projections 272 a, so that a similar engagement as previously described may be provided for positioning of the keys on the inner housing. Alternatively, the features could be reversed wherein the housing may include slots and the keys may include corresponding ridges.

In a variation of the displaceable key, a key 630 could be configured as depicted in FIG. 21. In an embodiment, the key 630 may have a longer body 650 so that more than half of the length of the body, for example about ⅗ to about ⅔ of the key body, will be covered by the outer housing 628, as depicted in FIG. 23A, when the outer housing is in its rest, or forward position. With this type of configuration, the guide rail 652 may be configured as a ‘fin-like’ projection extending from the body 650. As depicted in FIG. 22, a longitudinal slot 632 on the inner housing 626 may be configured for receipt of the rail 652 therein. Similar to the previously described embodiments, each of the top and bottom surfaces of the inner housing 626 may essentially be identical.

Since at least, for example, about ⅗ of the length of the key 630 may be disposed between the inner housing and the outer housing, the outer housing will essentially prevent lateral movement of the key away from the inner housing 626 when the outer housing is in its forward position as represented, for example by key 630 a in FIG. 23A in its forward, or ‘active’ position. In this position of the outer housing 628, the key 630 b will essentially be hidden in its rearward, or ‘inactive’ position. The guide rail 652 may therefore not require any widening at its end away from the body as was previously described for guide rail 552.

As in previous embodiments, the outer housing 628 may be displaceable rearwardly to a position as represented in FIG. 23B. In this embodiment, for example, only ⅓ to ⅖ of the ‘active’ key may then be covered by the outer housing. In this position of the outer housing 628 the ‘inactive’ key 630 b may be exposed for engaging the key to pull the key forward, if desired. The ‘active’ key 630 a may by pushed rearwardly into its ‘inactive’ position, and by changing the position of both keys, the polarity of the connector may be changed. Alternatively, as represented in FIG. 23C, when the outer housing 628 is in its rearward position, the keys 630 a and/or 630 b may be removed from the connector or inserted into position on the connector, as a flexibility of the material of the key may provide sufficient clearance for the fin 652 to be lifted out of its corresponding slot 632, so that a key may be pulled form or inserted into the connector.

In a further embodiment, as represented in FIGS. 24-26C, a connector 710 may include a snap-in key 730. Each of top or bottom walls 726 a or 726 b of the inner housing 726 may essentially be identical and include a slot 732 for receiving a snap-in projection of the key 730. The key 730 may include a key body portion 750 and a projecting engagement member 752 that is configured to fit into the slot 732 and retain the key 730 in engagement with the inner body 726. The engagement member 752 may be configured as a ‘snap-in’ type connector, wherein the engagement member may compress to fit through the slot 732 and then expand to retain member within the slot. In general, any type of ‘snap-in’ configuration may be usable.

In an embodiment as shown, the engagement member 752 may include first and second leg portions 747 a and 747 b separated by a slot that allows for the leg portions to be resiliently displaced towards one another for passage into and through the slot 732. Once through the slot 732 the leg portions 747 a, 747 b may return to their natural position. One or both of the leg portions 747 a, 747 b may include a catch 749 that projects outwardly from the leg portions to give the engagement member a width which is greater than a width of the slot 732. As represented in FIG. 26D, with an inner housing wall depicted in outline, when the leg portions 747 a, 747 b pass through the slot 732 in the inner housing wall and return to their normal positions, the catches can engage the inside surface of the housing wall to thereby provide a retention force against removing the key 730 from the inner housing 726.

The key body 750 may include recessed notches 745 along the longitudinal sides thereof to facilitate removal of the key 730 from the slot 732. The notches 745 may be configured to provide space for insertion of a tool, such as a small screwdriver, or even a fingernail, under the body 750 to apply a lifting force and pry the key 730 upwardly away from the inner housing 726. To prevent rotation of a key 730 on the inner housing 726, the engagement member 752 and slot 732 may have a length dimension (in a longitudinal direction of the key, or housing) that is at least twice as long as a width dimension transverse to the length dimension.

As an alternative to the ‘snap-in’ configuration, as represented in FIGS. 27 and 28A-28C, a key 830 may be configured with a twist-lock connector 852. The key 830 may include a connector 852 that extends away from the bottom surface of a body portion 850 of the key. The connector 852 may include a shaft portion 852 a that extends from the body portion 850 and an arm portion 852 b that extends away from the shaft portion. In an embodiment, the arm portion 852 b may extend from the shaft portion 852 a to only one side of the shaft as shown. Alternatively, the arm portion 852 b and shaft portion 852 a may be configured with a “T” configuration and the arm portion may extend bilaterally away from the shaft portion in opposite directions (not shown). The top and bottom walls 826 a and 826 b may include a corresponding passage 831 having a size and shape configured for passage of the arm portion 826 b therethrough. The shaft portion 852 a may have length extending from the body portion 850 so that the length may be substantially the same as the thickness of a wall portion of the top and bottom walls 826 a and 826 b at least in the vicinity of the passage 831. The arm portion 852 b, may thereby engage with an inner surface of the top or bottom walls 826 a and 826 b after being inserted through the passage 831 and then rotated about the shaft 852 a as represented in FIG. 29.

As shown in FIG. 29, the key 830 may be attached to either of the top or bottom walls 826 a and 826 b by aligning the key as represented by the dashed key outline (longitudinal axis of the key transverse to the longitudinal axis of the connector), inserting the arm portion 826 b through the opening 831 and rotating the key by about 90° to the ‘locked-in’ key position as represented by the solid key outline (longitudinal axis of the key aligned with the longitudinal axis of the connector). Once rotated, the arm portion 826 b as indicated by the dotted outline will no longer be aligned with the passage 831 and will be engaged with an interior surface of the top or bottom surfaces 826 a and 826 b to thereby prevent a lifting or removal of the key 830 away from the top or bottom walls.

To change the polarity of the connector, the key 830 may be rotated back to its transverse position (dashed line), lifted from the top or bottom walls 826 a, 826 b, and reinstalled on the opposite surface. To limit rotational movement of the key 830, the interior side of the walls may include a stop member 833, shown in FIG. 30A, which, upon rotation of the key about 90°, is engaged by the arm portion 826 b to block further rotation. The stop member may be provided by a thickening of the wall, a projection from the wall, or alternatively, the arm may rotate within a depression 859 extending into the wall from the interior towards the exterior, and which depression may have the shape of a quarter, or half of a circle, so that the sides of the depression may provide rotational stops.

In addition to, or as an alternative to the stop 833, in a manner similar to the embodiments of FIGS. 18A and 20A, a ridge 863 may be provided on the exterior surface of the top and bottom walls 826 a and 826 b, and the bottom surface of the key body 850 may include a corresponding slot 855 for engaging with the ridge upon rotation of the key 830 into its locked-in position. The ridge/slot configuration may also be configured to provide resistance to minimize inadvertent rotation of a key on the surfaces once a key is ‘lock-in’. If a stop 833 is not provided, the ridge/slot configuration would also provide a user a noticeable engagement to indicate a proper alignment of the key on the housing.

In an alternative embodiment (not shown) the shaft 852 a may be threaded with at least one circumferential thread and the opening 831 may include a matching thread and rotation of the shaft within the opening may thread the key into and out of the wall in a manner as would be represented by a nut and bolt engagement.

Various parts, components or configurations described with respect to any one embodiment above may also be adapted to any others of the embodiments provided.

This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope.

In the above detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

As used in this document, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term “comprising” means “including, but not limited to.”

While various compositions, methods, and devices are described in terms of “comprising” various components or steps (interpreted as meaning “including, but not limited to”), the compositions, methods, and devices can also “consist essentially of” or “consist of” the various components and steps, and such terminology should be interpreted as defining essentially closed-member groups.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

Various of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments. 

What is claimed is:
 1. A multi-fiber fiber optic connector comprising: a ferrule having a plurality of optical fibers supported therein; a housing disposed around at least a portion of the ferrule, the housing comprising: a first end for being inserted into a fiber optic adapter, a second end disposed opposite the first end, and at least a first wall portion extending from the first end towards the second end and a second wall portion opposite the first wall portion and extending from the first end towards the second end, wherein each of the first wall portion and the second wall portion have an internal surface disposed towards the ferrule and an external surface disposed outwardly away from the ferrule, and the housing defining a longitudinal axis in a direction from the first end to the second end, a transverse axis orthogonal to the longitudinal axis, and a vertical centerline through the first and second wall portions; and a key configured to be removably attached to either: the first wall portion to define a first keyed configuration for insertion of the first end into the adapter in only a first orientation to define a first polarity with respect to the adapter, or the second wall portion to define a second keyed configuration for insertion of the first end into the adapter in only a second orientation to define a second polarity with respect to the adapter, wherein the second polarity is opposite to the first polarity, wherein the key comprises: a first end configured for engaging with the housing adjacent the first housing end to prevent movement of the first key end with respect to the housing in at least a direction laterally away from the housing when removably attached to either the first wall portion or the second wall portion; and a second end disposed longitudinally away from the first end and configured for being removably attached to the housing at a second location of the housing spaced longitudinally from the first end of the housing towards the second end of the housing to prevent movement of the key with respect to the housing in at least a longitudinal direction along the housing when removably attached to either the first wall portion or the second wall portion.
 2. The connector of claim 1, wherein: each of the first wall portion and the second wall portion comprise a longitudinal slot extending from the first housing end towards the second housing end and disposed centrally on the wall portion at the vertical centerline, each slot having a depth extending from the external surface towards the internal surface along the vertical centerline, and defining a width transverse to the depth, wherein each slot has a first width at the external surface and a second width spaced from the external surface in the depth direction, wherein the second width is greater than the first width; and the key comprises a key body extending from the first key end to the second key end, the key body comprising a longitudinal guide rail projecting away from the key body and extending from the first key end towards the second key end, the guide rail having a first width adjacent the key body and a second width away from the key body, wherein the first and second widths of the guide rail correspond to the first and second widths of the slots for longitudinal insertion and movement of the guide rail within the slots.
 3. The connector of claim 2, wherein the key body adjacent the second key end comprises at least one of a projection and a recessed portion and the external housing surface comprises at least a corresponding other of a recessed portion and a projection, wherein a recessed portion and corresponding projection are configured for releasably engaging with one another for removably attaching the second key end to the housing at the second location of the housing.
 4. The connector of claim 2, wherein the key body adjacent the second key end comprises a recess and the housing comprises a projection configured for releasably engaging with the recess, wherein the projection and recess are configured to prevent longitudinal movement of the key with respect to the housing when the projection is engaged with the recess.
 5. The connector of claim 4, further comprising an outer housing movably disposed around at least a portion of the housing adjacent the second end of the housing, the outer housing having a first end portion disposed towards the first end of the housing and a second end disposed towards the second end of the housing, and the outer housing being movable longitudinally along the housing from a first position, wherein the first end portion of the outer housing is disposed about the second location of the housing, towards the second end of the housing to a second position wherein the first end portion of the outer housing is spaced away from the second location of the housing, wherein: the first end portion of the outer housing in the first position covers the second key end to prevent movement of the second key end laterally away from the housing and retain the recess of the key in engagement with the projection of the housing; and the first end portion of the outer housing in the second position is spaced longitudinally away from the second key end to allow for lateral movement of the second key end away from the housing for disengagement of the recess of the key from the projection of the housing to allow for longitudinal movement of the key along the housing
 6. The connector of claim 5, wherein: the key body has a first surface comprising the guide rail and a second surface disposed away from the first surface, wherein the second surface comprises at least one gripping feature for enhancing frictional engagement with the second surface; the recess of the key comprises a hole extending through the key body; the key body has a length and the guide rail extends about ¼ of the length of the key body from the first key end towards the second key end; the slots in the first wall portion and the second wall portion have a length from the first housing end towards the second housing end, and the length of the slots is substantially the same as the length of the guide rail; the projection has a front end disposed towards the first end of the housing and a back end disposed opposite the front end, wherein a height of the projection increases from the front end to the back end; and the connector comprises at least one biasing member for biasing the outer housing with respect to the inner housing from the second position to the first position.
 7. The connector of claim 6, wherein the key comprises a clip having a first end for releasably engaging the first end of the housing and a second end for releasably engaging with the housing at the second location when removably attached to either the first wall portion or the second wall portion.
 8. The connector of claim 7, wherein: each of the first wall portion and the second wall portion, at the first end of the housing, comprise a recessed notch configured for receiving the first clip end; and each of the first wall portion and the second wall portion, at the at the second location, comprises a slot for receiving the second clip end.
 9. The connector of claim 8, wherein each of the recessed notches and the slots are disposed centrally at a centerline of the first and second wall portions and have a longitudinal dimension transverse to the centerline;
 10. The connector of claim 8, wherein: the clip comprises a longitudinal body portion extending from the first clip end to the second clip end; the first clip end comprises a hook configured for hooking around the first end of the housing in the recessed notch; and the second clip end comprises a flange extending substantially orthogonally to the longitudinal body portion and configured for being inserted into the slot.
 11. The connector of claim 10, wherein: the hook has an arm portion that extends under the internal surface of the housing to prevent transverse movement of the first end of the hook away from the housing; the hook has a width orthogonal to the longitudinal dimension of the body portion and the recessed notch has a length corresponding to the width of the hook to prevent lateral movement of the hook within the recessed area; and the flange has a width orthogonal to the longitudinal dimension of the body portion and the slot has a length corresponding to the width of the flange to prevent lateral movement of the flange within the slot.
 12. The connector of claim 11, further comprising an outer housing movably disposed around at least a portion of the housing adjacent the second end of the housing, the outer housing having a first end portion disposed towards the first end of the housing and a second end disposed towards the second end of the housing, and the outer housing being movable longitudinally along the housing from a first position, wherein the first end portion of the outer housing is disposed about the second location of the housing, towards the second end of the housing to a second position wherein the first end portion of the outer housing is spaced away from the second location of the housing, wherein: the first end portion of the outer housing in the first position covers the second clip end to prevent movement of the second clip end transversely away from the housing and retain the flange of the clip within the slot of the housing; and the first end portion of the outer housing in the second position is spaced longitudinally away from the second clip end to allow for transverse movement of the second clip end away from the housing for disengagement of the flange from the slot to allow for longitudinal movement of the key along the housing.
 13. A housing for a fiber optic connector, the housing comprising: a first end for being inserted into a fiber optic adapter, and a second end disposed opposite the first end, wherein the housing defines a longitudinal direction from the first end to the second end, and a transverse direction orthogonal to the longitudinal direction; at least a first wall portion extending from the first end towards the second end and a second wall portion opposite the first wall portion and extending from the first end towards the second end, wherein each of the first wall portion and the second wall portion have an external surface disposed outwardly away from the ferrule; and a key configured to be removably attached to either: the first wall portion to define a first keyed configuration for insertion of the first end into the adapter in only a first orientation to define a first configuration with respect to the adapter, or the second wall portion to define a second keyed configuration for insertion of the first end into the adapter in only a second orientation to define a second configuration with respect to the adapter, wherein the key comprises one of a snap-in fastener and a twist lock fastener configured for engaging with either the first wall portion or the second wall portion; and each of the first wall portion and the second wall portion comprises an opening configured for receiving the snap-in fastener or the twist in fastener to releasably retain the key with either the first wall portion or the second wall portion.
 14. The housing of claim 13, wherein: the key has a planar base portion defining a top surface for being disposed away from the first or second wall portion and a bottom surface for being disposed adjacent the first or second wall portion, and the key comprises a snap-in fastener extending from the bottom surface transverse to the planar base portion, and each of the first and second wall portions comprises an opening configured for receiving the snap-in fastener and releasably retaining the snap-in fastener therein.
 15. The housing of claim 13, wherein: the key has a planar base portion defining a top surface for being disposed away from the first or second wall portion and a bottom surface for being disposed adjacent the first or second wall portion, and the key comprises a twist-lock element extending from the bottom surface transverse to the planar base portion, and each of the first and second wall portions comprises an opening configured for receiving the twist-lock element and releasably retaining the twist-lock element therein.
 16. A method of switching the polarity configuration between a multi-fiber fiber optic connector and a corresponding adapter configured for receiving the connector, wherein the connector has a connector housing comprising a first end for being inserted into the adapter, a second end disposed opposite the first end, and at least first and second movably displaceable keys displaceable along the housing between a first position adjacent the first end and a second position disposed towards the second end, and wherein one of the first and second keys is in its first position and the other of the first and second keys is in its second position to provide a first polarity for the fiber optic connector, the method comprising: slidingly displacing the first key from its corresponding first or second position to the other of the first and second positions, and slidingly displacing the second key from its corresponding first or second position to the other of the first and second positions, to provide a second opposite polarity for the fiber optic connector. 